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Table 1 Exposure Definitions

From: A novel weighting method to remove bias from within-subject exposure dependency in case-crossover studies

  Case period Control periods
Definition I Last day Last day
Definition II Last day Half or more days
Definition III Last day Any 1 day
Definition IV Any 1 day Any 1 day
  1. Last day = exposure status of the period was the exposure status on the last day; Half or more days = exposure status of the period is defined as ‘exposed’ if at least half of days during the period was exposed and ‘unexposed’ otherwise; Any 1 day = exposure status of the period is defined as ‘exposed’ if at least 1 day during the period is exposed and ‘unexposed’ otherwise